Name: __________________________ Period:____

Evidence of Evolution

Background

When Charles Darwin first proposed the idea that all new species descend from an ancestor, he performed an exhaustive amount of research to provide as much evidence as possible.  Today, the major pieces of evidence for this theory can be broken down into the fossil record, embryology, comparative anatomy, and molecular biology.

 

Fossils

This is a series of skulls and front leg fossils of organisms believed to be ancestors of the modern-day horse. 

 

Source:  http://www.iq.poquoson.org

1.  Give two similarities between each of the skulls that might lead to the conclusion that these are all related species.

 

 

 

2.  What is the biggest change in skull anatomy that occurred from the dawn horse to the modern horse?

 

 

 

3. What is the biggest change in leg anatomy that occurred from the dawn horse to the modern horse?

 


 

 

Embryology

Organisms that are closely related may also have physical similarities before they are even born!  Take a look at the six different embryos below:

 

Source:  http://www.starlarvae.org

 

Hypothesize which embryo is from each of the following organisms by matching the letter of the embryo with the species.

 

Species

Embryo (letter)

Species

Embryo (letter)

Human

 

Tortoise

 

Chicken

 

Salamander

 

Rabbit

 

Fish

 

 

These are older, more developed embryos from the same organisms.

 

Hypothesize which embryo is from each of the following organisms by matching the letter of the embryo with the species.

 

Species

Embryo (letter)

Species

Embryo (letter)

Human

 

Tortoise

 

Chicken

 

Salamander

 

Rabbit

 

Fish

 

 

  

These are embryos at their most advanced stage, shortly before birth.

 

Describe how the embryos changed for each of these organisms from their earliest to latest stages.

 

1.      Look again at the six embryos in their earliest stages.  Describe the patterns you see.  What physical similarities exist between each of the embryos? (name at least 3)

 

 

 

 

2.      The human embryo was letter F. Which organismís embryo(s) became different from the human embryo the earliest in development?

 

 

3.      What does this say about the relatedness of this(ese) organism(s) and humans?

 

 

4.      Which organismís embryo(s) where the same as the human embryo the longest in development?

 

 

5.      What does this say about the relatedness of this organism and humans?

 

 

 

 

 

 

 

 

 


 

 

Comparative Anatomy

Shown below are images of the skeletal structure of the front limbs of 6 animals:  human, crocodile, whale, cat, bird, and bat.  Each animal has a similar set of bones.  Color code each of the bones according to this key:

 

Humerus    [red]

 

Ulna           [blue]

 

Radius        [green]

Carpals                   [orange]

 

Metacarpals            [yellow]

 

Phalanges               [purple]

 

 

For each animal, indicate what type of movement each limb is responsible for.

 

Animal

Primary Functions

Human

Using tools, picking up and holding objects

Whale

 

Cat

 

Bat

 

Bird

 

Crocodile

 

 

Compare the skeletal structure of each limb to the human arm. Relate the differences you see in form to the differences in function.

 

Animal

Comparison to Human Arm in Form

Comparison to Human Arm in Function

Whale

Whale has a much shorter and thicker humerus, radius, and ulna.  Much longer metacarpals.  Thumb has been shortened to a stub.

The whale fin needs to be longer to help in movement through water.  Thumbs are not necessary as the fins are not used for grasping.

Cat

 

 

 

 

 

Bat

 

 

 

 

 

 

 

1.      Are the structures above examples of homologous, analogous or vestigial structures?

 

 

2.      Does this suggest an evolutionary relationship? 

 

 

 

 

 

 

Compare the anatomy of the butterfly and bird wing below.

 

 

 

1.  What is the function of each of these structures?

 

 

2.      How are they different in form?  Give specific differences.

 

 

 

3.      Are these structures examples of homologous, analogous or vestigial structures?

 

 

4.      Does this suggest an evolutionary relationship? 

 

Compare the overall body of the cave fish and the minnow below.

 

 

 

1.  What is the biggest, most obvious difference between these two fish?

 

 

2.  Assume the two fish came from the same original ancestor.  Why might the cave fish have evolved without eyesight? 

 

 

3.      Is this an example of homologous, analogous or vestigial structures?

 

 

4.      Does this suggest an evolutionary relationship?